Water-based Lignin-Particle-Epoxy Surface Coatings, Thermosets and Adhesives

Abstract

According to an example aspect of the present invention, there is provided a composition comprising colloidal lignin particles and an epoxy compound.

1 . A composition comprising colloidal lignin particles and an epoxy compound. 
     
     
         2 . The composition according to  claim 1 , wherein the colloidal lignin particles are dispersed in an aqueous dispersion. 
     
     
         3 . The composition according to  claim 1  or  2 , wherein the aqueous dispersion has a concentration of colloidal lignin particles up to 50 wt. %. 
     
     
         4 . The composition according to any of  claims 1 to 3 , wherein the aqueous dispersion has a concentration of colloidal lignin particles in the range of 5 to 20 wt. %. 
     
     
         5 . The composition according to any of the preceding  claims  further comprising one or more organic solvents, suitably organic volatile solvents. 
     
     
         6 . The composition according to any of the preceding  claims , further comprising one or more organic solvents selected from the group consisting of ethanol, tetrahydrofuran and acetone. 
     
     
         7 . The composition according to any of the preceding  claims , wherein water comprises more than 70 vol% in relation to the one or more organic solvents. 
     
     
         8 . The composition according to any of the preceding  claims , wherein the epoxy compound is a hydrophilic compound. 
     
     
         9 . The composition according to any of the preceding  claims , wherein the epoxy compound is glycerol diglycidyl ether. 
     
     
         10 . The composition according to any of the preceding  claims  having a molar epoxy/colloidal lignin particle ratio of up to 1.5:1. 
     
     
         11 . The composition according to any of the preceding  claims  having a molar ratio of epoxy group to hydroxyl groups between 1.5:1 - 0.2:1, preferably 1:1 - 0.6:1. 
     
     
         12 . The composition according to any of the preceding  claims  having a concentration of colloidal lignin particles of 10 - 20 wt. % of the composition. 
     
     
         13 . The composition according to any of the preceding  claims   having a concentration of colloidal lignin particles of 30 wt.% or more of the composition, typically in the range of 50 to 80 wt. %of the composition, preferably 70 wt. % of the composition. 
     
     
         14 . The composition according to any of the preceding  claims , further comprising one or more curing initiators or additives. 
     
     
         15 . The composition according to any of the preceding  claims , wherein the colloidal lignin particles are spherical. 
     
     
         16 . The composition according to any of the preceding  claims , wherein the colloidal lignin particles have a diameter in the range of 10 - 2000 nm, preferably 100 - 1500 nm, suitably 500 - 1000 nm. 
     
     
         17 . The composition according to any of the preceding  claims , wherein the colloidal lignin particles have a surface charge in the range of -100 - 50mV, suitably -50 - 40 mV, preferably -10 - 10 mV, measured by zeta potential. 
     
     
         18 . The composition according to any of the preceding  claims  further comprising a plasticiser. 
     
     
         19 . A surface coating comprising the composition of any of  claims 1 to 18 . 
     
     
         20 . An adhesive comprising the composition of any of  claims 1 to 18 . 
     
     
         21 . A method for manufacturing a composition according to any of the preceding  claims  comprising the steps of
 • providing colloidal lignin particles, 
 • providing an epoxy containing compound, and 
 • mixing the epoxy compound and the colloidal lignin particles to form a composition. 
 
     
     
         22 . The method according to  claim 21  comprising the further step of dispersing the colloidal lignin particles in water to form an aqueous dispersion. 
     
     
         23 . The method according to  claim 21  or  22  comprising the further step of adding an organic solvent. 
     
     
         24 . The method according to any of claims  claim 21 to 23  comprising the further step of adding a plasticiser. 
     
     
         25 . The method according to any of  claims 21 to 24  comprising the further step of adding one or more curing initiators or additives. 
     
     
         26 . A method of coating a surface comprising the steps of
 • applying a composition according to any of  claims 1 to 19 , obtainable by a method according to any of  claims 21 to 25  to a surface to be coated,   • heating the coated surface to initiate a curing reaction.   
     
     
         27 . The method according to  claim 25  or  26 , wherein the composition is applied to the surface with a brush, with a glass rod, with a steel rod and/or by spraying. 
     
     
         28 . The method according to any of  claims 25 to 27 , wherein the coated surface is heated using an oven, using radiation, using hot air and/or using a heating plate. 
     
     
         29 . The method according to any of  claims 25 to 28 , wherein the coated surface is heated to a temperature up to 350C, preferably 50 to 150C. 
     
     
         30 . The method according to any of  claims 25 to 29  comprising the step of prewetting the surface to be coated. 
     
     
         31 . The method according to any of  claims 25 to 30 , comprising the step of preheating the surface to be coated, particularly to a temperature up to 350C, typically not more than 75C. 
     
     
         32 . A method of coating a surface comprising the steps of 
 • applying colloidal lignin particles to a surface to be coated, and   • applying an epoxy compound to the surface to be coated in a separate step.   
     
     
         33 . The method according to  claim 32 , further comprising adding one or more curing initiators and/or additives to the surface to be coated. 
     
     
         34 . The method according to  claim 32  or  33 , wherein each component is applied to the surface with a brush, with a glass rod, with a steel rod and/or by spraying. 
     
     
         35 . The method according to any of  claims 32 to 34 , wherein the coated surface is heated using an oven, using radiation, using hot air and/or using a heating plate. 
     
     
         36 . The method according to any of  claims 32 to 35 , wherein the coated surface is heated to a temperature up to 350C, preferably 50 to 150C. 
     
     
         37 . The method according to any of  claims 32 to 36  comprising the step of prewetting the surface to be coated. 
     
     
         38 . The method according to any of  claims 32 to 37 , comprising the step of preheating the surface to be coated, particularly to a temperature up to 350C, typically not more than 75C. 
     
     
         39 . A method of adhering a surface of a first substrate to a surface of a second substrate comprising the steps of
 • applying a composition according to any of  claims 1 to 20  obtainable by a method according to any of  claims 21 to 25  to coat a surface of a first substrate,   • pressing the coated surface of the first substrate with a surface of a second substrate,   • heating the pressed material to a temperature up to 350C.   
     
     
         40 . The method according to  claim 39 , wherein the first substrate and the second substrate are of the same material. 
     
     
         41 . The method according to  claim 39 , wherein the first substrate and the second substrate are of a different material. 
     
     
         42 . A method of stabilizing colloidal lignin particles comprising the steps of 
 • providing an aqueous dispersion of colloidal lignin particles,   • providing an epoxy compound,   • combining the aqueous dispersion with the epoxy compound,   • heating and stirring the dispersion, and   • recovering cured CLPs.   
     
     
         43 . The method according to  claim 42 , wherein the epoxy compound is dissolved or mixed in a solvent, preferably dissolved or mixed in water. 
     
     
         44 . The method according to  claim 42  or  43 , wherein the solubility of the epoxy compound is increased with a volatile organic solvent prior to combining the epoxy compound with the aqueous dispersion of colloidal lignin particles. 
     
     
         45 . The method according to any of  claims 42 to 44 , wherein the mixing is carried out for a period of 10 minutes to 24 hours, preferably 30 minutes to 18 hours, suitably 1 hour to 12 hours, particularly 2 hours to 8 hours, typically 3 to 7 hours, advantageously 4 to 6 hours, optionally 5 hours. 
     
     
         46 . Cured lignin particles obtainable buy a method according to any of  claims 42 to 45 . 
     
     
         47 . A method of epoxidising lignin using CLPs as a lignin precursor, said method comprising the steps of
 • dispersing CLPs in water   • heating under reflux,   • adding epichlorhydrin is added,   • adjusting pH to 12 to 14, by the addition of a base, to initiate the reaction, and   • neutralizing the solution with an acid to stop the reaction.   
     
     
         48 . The method according to  claim 47 , wherein the dispersion is heated under reflux to 65C. 
     
     
         49 . The method according to  claim 47  or  48 , epihydrochlorin is added in an amount of 5 -10 ml/g CLP, typically using a molar epichlorohydrin to lignin hydroxyl group ratio of 7:1 - 14:1. 
     
     
         50 . The method according to any of  claims 47 to 49 , wherein the pH is adjusted with NaOH in the pH adjusting step. 
     
     
         51 . The method according to any of  claims 47 to 50 , wherein the pH is adjusted to ca. 13 in the pH adjusting step. 
     
     
         52 . The method according to any of  claims 47 to 51 , wherein the reaction is neutralized with HC1 to stop the reaction. 
     
     
         53 . The method according to any of  claims 47 to 52 , further comprising recovering epoxidised lignin. 
     
     
         54 . Epoxidised lignin obtainable by a method according to any of  claims 47 to 53 . 
     
     
         55 . A thermoset formed from a composition according to any of  claims 1 to 18 . 
     
     
         56 . A thermoset formed from an epoxidised lignin according to  claim 54  and colloidal lignin particles. 
     
     
         57 . A method of forming a thermoset comprising the steps of 
 • providing a dispersion of colloidal lignin particles   • providing an epoxy compound,   • mixing the dispersion of colloidal lignin particles and the epoxy compound in a centrifuge,   • recovering a supernatant, and   • heating the supernatant at a temperature in the range of 40 - 350 C.   
     
     
         58 . A thermoset according to  claim 55  or  56  obtainable by a method according to  claim 57 .